WHEN TO SPRAY OR NOT TO SPRAY

there are lots of questions this spring with regard to nitrogen application on wheat. How early should we go? Does split nitrogen make sense? Should we use “protected” nitrogen this year? Let’s look at the data.

A few growers put nitrogen on in February. NO!!! Research data clearly shows that nitrogen should not be applied on wheat in February. Dr. Ed Lentz from Ohio State University has proven that February application of nitrogen has no yield benefit and a very high risk of nitrogen loss. In the same vein, manure should not be spread on wheat in February. It is simply too early for any N source!

A lot of growers whose wheat crop struggled last fall are asking if they should apply nitrogen to stimulate growth and increase the chances of a good wheat crop. “Ample research out of Ontario and Ohio indicates that this will result in very little yield benefit; only 1-2 bushels per acre.”?“However, in a year with few fall tillers, a little early N is the best you can do to help the crop along.”

check the quality of your wheat crop
If you have a questionable wheat crop and hope to keep it, a little nitrogen early is the best management strategy we have. Apply 30 lb/acre in mid-March to try and stimulate the wheat crop.

If you are a grower with good wheat — and there are some excellent wheat fields — there is no reason to split apply nitrogen. Growers with good wheat, or those who are able to drive over their field in mid-to-late April, should apply all of their nitrogen in a single application in the last half of April or very early May.

For growers on heavy clay soil (Niagara, Essex, south Lambton) the practical aspect of when you can travel on the field becomes more limiting. These growers may find the best timing for a single N application is on the last frosts in late March or early April. Otherwise, soil conditions may prevent application until mid-May. Based on what was learned from last year, those with heavy clay soil who did not apply until May 15th or later did not give up much yield. The wheat may go yellow, but it can compensate and rebound and the yield loss associated with later than ideal nitrogen application will not be significant.

environmentally stable nitrogen (ESN)
Some growers have questioned if applying ESN (polycoated urea, 44% N) will solve the February application concerns. Theoretically ESN won’t release in February as it requires warm temperatures and moisture to become available. It will sit on the soil surface until the weather is right for release. This presents a two-fold problem. First, if we do have a rainfall or snowmelt event, the granules can float and move with the water and application uniformity will be compromised. Second, if warm weather arrives in early March, it can release earlier than expected and N losses will be a potential concern. Stabilized nitrogen products such as ESN or Agrotain Plus reduce the risk of very early N applications, however they do not eliminate the problem.

the bottom line
Do not apply nitrogen on wheat in February! Where growers do want to split apply nitrogen, 30 pounds in mid-March is ample — but only if your wheat crop is questionable. •

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